1. Assembly Language programming
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Assembly Language programming

2. Assembly Language programming
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Assembly Language programming
Assembly language is mnemonic representation of machine code
Instruction has mnemonics (text form)
Instruction decoder generates opcode
Opcode is machine code
It helps to learn internal architecture of computer
Programs requires less space in assembly language

3. Assembly Language Development
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MOV AX, BX ..
Assembler
OBJ
LIB
Errors
Linked Modules
Loader
Linker
Main Memory

4. Assembler MASM (Microsofts micro assembler)
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Assembler
MASM (Microsofts micro assembler)
TASM (Borland Turbo assembler)
NASM (Netwide assembler)
It converts instructions into binary code
It generates two files( .OBJ file and .LST file)
Object file contains binary code of instruction and address of instruction
List file contains program statements, binary code of each instruction and offset of eachinstruction

5. LINKER It is used to join many object files into one file
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LINKER
It is used to join many object files into one file
Large programs are divided into smaller files
Link file contains binary code of all combined modules
It produces .Exe file

6. LOADER It is used to LOAD FILE in memory It assigns specific address
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LOADER
It is used to LOAD FILE in memory
It assigns specific address
It converts .EXE file into .BIN file which has physical address
EXE2BIN

7. Assembly Instruction Format
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Assembly Instruction Format
Label :
Mnemonics
Operand1,
Operand2
; Comments
Label – Symbolic Name Assigned to First Byte of Instruction
Mnemonics – Operation to be performed
Operands – Operation to be performed on.
Comments – Documentation, Non Executable .

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Assembler Directives
These are not the part of processor instruction set.
Instructions to assembler, linker and loader.
Also referred as pseudo-operations.
They enable to control the way in which program assembles and lists.
Act during assembly of program and do not generate any machine executable code.

9. Classification Segment Simplification Data Allocation Segment Related
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Classification
Segment Simplification
Data Allocation
Segment Related
Macros Declarations
Code label
Scope Declaration
Listing Control
Miscellaneous

10. Segment Simplification
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Segment Simplification
.CODE :beginning of code segment
Ex .CODE [name]
.DATA : beginning of Data Segment
.STACK :used for defining stack
Ex .STACK [size]
.EXIT
.MODEL :used for selecting standard memory model
Ex .MODEL [Memory model]

11. Memory Models Model No. of code segments No. of data Small
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Memory Models
Model
No. of code
segments
No. of data
Small
One CS <=64KB
One DS<=64KB
Medium
Any no. and any
size
Compact
Large
Huge

12. Data allocation DB :define byte type of variable
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Data allocation
DB :define byte type of variable
DW :define variable of 1 word length
DD :define double word
DQ :define quad(4) word
DT :define ten bytes (stores no in decimal form)
EQU :Equate
ORG :originate , it is used to set location pointer at desired location in program
e.g. org 500h

13. Segment related SEGMENT :indicates start of logical segment
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Segment related
SEGMENT :indicates start of logical segment
ENDS : indicates end of segment
END :last statement of program
ASSUME :used to tell assembler name of logical segment
GROUP :collect segment of same type under one name
e.g. NAME GROUP SEG1, SEG2

14. scope PUBLIC EXTRN e.g. PUBLIC VAR1, VAR2
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scope
PUBLIC
e.g. PUBLIC VAR1, VAR2
Var1 and var2 is to be referred from other module
EXTRN
e.g. EXTRN SQRT : FAR
Labels are in other module

15. Listing control PAGE TITLE PAGE [length], [width] e.g. PAGE 10, 35
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Listing control
PAGE
PAGE [length], [width]
e.g. PAGE 10, 35
Maximum no of lines on a page
Maximum no of characters in line
TITLE
TITLE text
e.g. TITLE MY FIRST PROGRAM

16. Code Label ALIGN EVEN LABEL PROC ALIGN number e.g. ALIGN 16
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Code Label
ALIGN
ALIGN number
e.g. ALIGN 16
EVEN
e.g. EVEN NAME DB 5 DUP(0)
LABEL
e.g. NEXT LABEL FAR
PROC
procedure-name PROC type

17. Macro Declarations MACRO and ENDM DISP MACRO ENDM MOV DL, AL
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Macro Declarations
MACRO and ENDM
DISP MACRO
MOV DL, AL
MOV AH, 4CH
INT 21H
ENDM

18. Miscellenous INCLUDE NAME GLOBAL INCLUDE path:file name
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Miscellenous
INCLUDE
INCLUDE path:file name
NAME
Assign name to each assembly module
GLOBAL
GLOBAL variable-name